mcpcap

A modular Python MCP (Model Context Protocol) Server for analyzing PCAP files. mcpcap enables LLMs to read and analyze network packet captures from local or remote sources, providing structured JSON responses about network traffic.

Overview

mcpcap uses a modular architecture to analyze different network protocols found in PCAP files. Each module focuses on a specific protocol, allowing for targeted analysis and easy extensibility. The server leverages the powerful scapy library for packet parsing and analysis.

Key Features

• Modular Architecture: Easily extensible to support new protocols
• Local & Remote PCAP Support: Read files from local directories or HTTP servers
• Scapy Integration: Leverages scapy's comprehensive packet parsing capabilities
• MCP Server: Integrates seamlessly with LLM clients via Model Context Protocol
• JSON Responses: Structured data format for easy LLM consumption

Installation

mcpcap requires Python 3.10 or greater.

Using pip

pip install mcpcap

Using uv

uv add mcpcap

Using uvx (for one-time usage)

uvx mcpcap

Quick Start

1. Start the MCP Server:

   Local PCAP file:

   mcpcap --pcap-path /path/to/specific/file.pcap
   

   Local PCAP directory:

   mcpcap --pcap-path /path/to/pcap/files
   

   Remote PCAP file:

   mcpcap --pcap-url https://example.com/sample.pcap
   

   With advanced options:

   mcpcap --pcap-path /path/to/pcaps --max-packets 100 --protocols dns
   

2. Connect your LLM client to the MCP server

3. Ask questions about your network traffic:

   • "What domain was queried the most in the DNS traffic?"
   • "Show me all DNS queries for example.com"
   • "What are the top 5 queried domains?"

Modules

mcpcap supports multiple protocol analysis modules:

DNS Module

The DNS module analyzes Domain Name System packets in PCAP files.

Capabilities:

• Extract DNS queries and responses
• Identify queried domains and subdomains
• Analyze query types (A, AAAA, MX, etc.)
• Track query frequency and patterns
• Identify DNS servers used

DHCP Module

The DHCP module analyzes Dynamic Host Configuration Protocol packets in PCAP files.

Capabilities:

• Track DHCP transactions (DISCOVER, OFFER, REQUEST, ACK)
• Identify DHCP clients and servers
• Monitor IP address assignments and lease information
• Analyze DHCP options and configurations
• Detect DHCP anomalies and security issues

Example Usage:

# Analyze DHCP traffic only
mcpcap --pcap-path /path/to/dhcp.pcap --modules dhcp

# Analyze both DNS and DHCP
mcpcap --pcap-path /path/to/mixed.pcap --modules dns,dhcp

Configuration

PCAP Sources

mcpcap supports multiple ways to specify PCAP data sources:

Local PCAP File:

mcpcap --pcap-path /local/path/to/specific.pcap

Local Directory:

mcpcap --pcap-path /local/path/to/pcaps

Remote PCAP File (Direct Link):

mcpcap --pcap-url https://wiki.wireshark.org/uploads/dns.cap

Remote Directory Listing:

mcpcap --pcap-url http://example.com/pcaps/

Analysis Options

Module Selection:

# Single module
mcpcap --modules dns --pcap-path /path/to/files

# Multiple modules
mcpcap --modules dns,dhcp --pcap-path /path/to/files

Protocol Selection (automatically matches loaded modules):

# DNS analysis only
mcpcap --modules dns --pcap-path /path/to/files

# DHCP analysis only  
mcpcap --modules dhcp --pcap-path /path/to/files

# Both DNS and DHCP analysis
mcpcap --modules dns,dhcp --pcap-path /path/to/files

Packet Limiting (for large files):

mcpcap --max-packets 1000 --pcap-path /path/to/files

Combined Options:

mcpcap --pcap-path /data/capture.pcap --max-packets 500 --modules dns,dhcp

CLI Reference

mcpcap [--pcap-path PATH | --pcap-url URL] [OPTIONS]

Source Options (choose one):

• --pcap-path PATH: Local PCAP file or directory
• --pcap-url URL: Remote PCAP file URL or directory listing

Analysis Options:

• --modules MODULES: Comma-separated modules to load (default: dns)
  • Available modules: dns, dhcp
  • Protocols are automatically set to match loaded modules
• --max-packets N: Maximum packets to analyze per file (default: unlimited)

Examples:

# Analyze specific file
mcpcap --pcap-path ./capture.pcap

# Remote file with packet limit
mcpcap --pcap-url https://example.com/dns.cap --max-packets 100

# Directory with DHCP analysis
mcpcap --pcap-path /captures --modules dhcp

Example

An example PCAP file (dns.pcap) containing DNS traffic is included in the examples/ directory to help you get started.

Architecture

mcpcap's modular design makes it easy to extend support for new protocols:

1. Core Engine: Handles PCAP file loading and basic packet processing
2. Protocol Modules: Individual modules for specific protocols (DNS, etc.)
3. MCP Interface: Translates between LLM queries and packet analysis results
4. Output Formatter: Converts analysis results to structured JSON

Adding New Modules

New protocol modules can be added by:

1. Implementing the module interface
2. Defining scapy display filters for the protocol
3. Creating analysis functions specific to the protocol
4. Registering the module with the core engine

Future modules might include:

• BGP (Border Gateway Protocol)
• HTTP/HTTPS traffic analysis
• TCP connection tracking
• And more!

Remote Access

mcpcap supports reading PCAP files from remote HTTP servers in two modes:

Direct File Access: Point directly to a PCAP file URL

mcpcap --pcap-url https://wiki.wireshark.org/uploads/__moin_import__/attachments/SampleCaptures/dns.cap

Directory Listing: Parse HTML directory listings to find PCAP files

mcpcap --pcap-url http://server.com/pcap-files/

Supported File Types: .pcap, .pcapng, .cap

Current Limitations:

• HTTP/HTTPS only (no authentication)
• Directory listings require standard HTML format
• Files are downloaded temporarily for analysis

Future versions may include support for Basic Authentication and other security mechanisms.

Contributing

Contributions are welcome! Whether you want to:

• Add support for new protocols
• Improve existing modules
• Enhance the MCP interface
• Add new features

Please feel free to open issues and submit pull requests.

License

MIT

Requirements

• Python 3.10+
• scapy (packet parsing and analysis)
• requests (HTTP remote file access)
• fastmcp (MCP server framework)
• All dependencies are automatically installed via pip

Documentation

Full documentation is available at docs.mcpcap.ai

Support

For questions, issues, or feature requests, please open an issue on GitHub.